Description: Two different forms with differing apices are documented here. Valves are moderately dorsiventral and narrow-lanceolate in outline in the most widespread form. Dorsal margin is more clearly curved relative to the weakly convex ventral side, without shoulders. Poles are rostrate and may be weakly deflected ventrally, but variable in populations. Axial area very narrow and central area absent to weakly developed. Length 9.6–23.5 μm; width 2.6–3.8 μm; maximum L:W ratio 7.0.A more clearly capitate form with a near lanceolate outline (Figs 461–472) was found with type material of E. alpina and also occurs in calcareous lakes in Ireland. It shares the same ultrastructural combination of features as E. krammeri, including identical raphe design, a characteristic thin plate-like silica thickening visible internally between the helictoglossa and apices (Fig. 442; 479–480) and transapically elongate linear shaped puncta. Striae density is higher (32–36 in 10 μm) in these populations than originally published for E. krammeri.

Ecology: A cosmopolitan and widespread diatom found in 31 lakes and reaching a maximum relative abundance of 43%. It occurs at higher densities in calcareous lakes in oligotrophic to mesotrophic conditions (Fig. 532).